November 7, 2012

European Settlement Caused Collapse Of Great Barrier Reef Coral

Australia´s Great Barrier Reef, the largest coral system in the world, so big that it can be seen from space, is one of the planet´s most remarkable natural wonders. But researchers from University of Queensland have now revealed this precious ecosystem is not faring so well. The problem: European settlement and extensive degradation on mainland Australia.

The expansion of European settlement in Australia has been contributing to the historic collapse of coral in the Great Barrier Reef for more than 60 years, the researchers explained. This expansion caused coral collapse between the 1920s and the 1950s as settlers incorporated farming as a source of living, noted lead researcher John Pandolfi and his colleagues.

According to MSNBC, Pandolfi, a marine biologist at UQ, said a “very significant shift in the coral community composition” in the Great Barrier Reef was linked to “colonization of Queensland.”

Europeans began to settle in Queensland in the 1860s, wiping out forests to make room for grazing sheep and sugar plantations. By the 1930s, large amounts of fertilizer, pesticides and waste ran into rivers and streams and then into the ocean.

Publishing their findings in the Nov. 6 issue of the Proceedings of the Royal Society B, the researchers explained that this farming runoff clouded the pristine waters off the coast of Queensland and killed the natural branching coral species, leaving a stunted, weedy type of coral in its place.

While past studies reported that tourism and climate change were largely affecting the coral reef system, the researchers said human settlers were disrupting the reef´s ecology long before.

To prove their theory, Pandolfi and his crew drilled sediment cores, 6.5 to 16.5 feet long, from the seafloor at Pelorus Island, which is in the thick of the coral reef ecosystem. The core samples confirmed that healthy branching Acropora corals flourished for centuries before settlement of the region. Even the evidence of flooding and cyclonic events had not disrupted the reef on such a scale that human settlement had.

Further analysis of the core samples, showed that sometime between 1920 and 1950, the branching Acropora failed to recover from the long-term disruptions.

Pandolfi and his team, from the ARC Centre of Excellence for Coral Reef Studies (CoECRS) at UQ, said their sampling adds weight to evidence that human activity can be attributed to the recent loss of up to half of the corals in the Great Barrier Reef.

Study co-lead author, George Roff, also of CoECRS, said the destruction of branching corals coincided with wide-spread land clearing for grazing and agriculture in the 19th century. This extensive degradation caused an increase in the amount of slurry being deposited into the waters of the Great Barrier Reef.

“Corals have always died from natural events such as floods and cyclones, but historically have shown rapid recovery following disturbance. Our results suggest that the chronic influence of European settlement on the Queensland coastline may have reduced the corals ability to bounce back from these natural disturbances” he said in a press release.

The team found two sites along the GBR where Acropora corals have vanished completely and a third area where there was a notable shift from Acropora to Pavona corals. This shift is similar to observations taken in the Caribbean, where human activities have also disrupted coral reef habitat.

“On a global scale, our results are consistent with a recent report from the Caribbean region, where land use changes prior to 1960 were implicated in a significant decline in Acropora corals in near-shore reefs,” said the researchers in the press release.

“The research underlines that there is a very strong link between what we do on land — and what will happen to the Great Barrier Reef in future. It encourages us to take greater and more rapid steps to control runoff and other impacts on land,” said Pandolfi.

While the findings suggest humans have been damaging reefs far longer than previously thought, the problem has a straightforward solution: reduce runoff. “Any kind of measures that are going to improve the water quality should help those reefs to recover,” concluded Pandolfi.